68 ATLAS OF BIOLOGY. 



FIG. IX. Oblique transverse section across B. of the same, to show the so-called 

 liver, the main bile-ducts, and the relations of the lesser retractor muscles. 



The above sections were made from a fresh specimen, some few hours after death. 

 All x li, 



FIG. X. The nervous system, dissected from the left side, only such additional parts 

 being indicated as are concerned in ascertaining its course. 



The pallial lobe and gills were removed, the excretory organ of the left side was slit 

 open, and its contents washed out. 



The cerebral ganglia having next been found, the body-wall, liver, and genital gland 

 were in part removed as indicated cutting in a line with the tendon of the protractor pedis 

 muscle, in order to expose the whole course of the cerebro-splanchnic commissure, c.p.s. 

 Nat. size. 



The so-called parieto-splanchnic ganglia of the Lamellibrancli have been shown by 

 Spengel (81) to represent the olfactory ganglia of other molluscs. 



FIG. XI. Oblique transverse section across the oral region of Fig. X., to show the 

 relations of the supraoesophageal nerve-commissure, the pedal ganglia, and, on the left 

 side, the whole course of the cerebro-pedal commissure. 



The valve and labial palps of the left side were for the most part removed, the origins 

 of the tendon of the anterior pedal muscles being shown incidentally. Nat. size. 



FIG. XII. Ciliated and other cells, scraped from the lining membrane of the intestine. 

 The two lower ones were active in the production of a secretion. D. 3. 



FIG. XIII. Three ovarian ova, at different stages, teased out in eosin solution. D. 3. 

 The protoplasmic filament passing through the micropyle, inc., represents the torn neck 

 of attachment to the germinal epithelium. See Von Jehring (67). 



FIG. XIV. Transverse section of the valve, cut at right angles to its long axis. 

 Prepared as described for the Crayfish shell (Plate X., Fig. VIII.) A. 3. 



FIG. XV. Tangential section across the prismatic layer of the same. D. 2. 



i 



FIG. XVI. The GlocMdium larva, from the gills of an animal killed under chloroform. 

 Spirit material, stained with magenta. 



FIG. XVII. The same, seen from the left side. 

 The dots on the valve represent pore canals. 



